Adding a Request Participant in new issue view doesn't actually add them to the ticket

Issue Summary

Adding a Request participant (or Request participants) in new issue view doesn't actually add them to the ticket.

Steps to Reproduce

1. View a ticket in new issue view
2. Add a Request participant
3. Refresh the page
4. Observe that the Request participant field has not changed and the history shows it never occurred

Expected Results

The Request participant is added.

Actual Results

The page shows them as added until refreshing and seeing they were never added to begin with.

• https://share.getcloudapp.com/GGuAX2m0

Workaround

Adding the Request participant in the old issue view works (clicking the link at the top of the ticket to go there or appending ?oldIssueView=true to the end of the URL). But if you get back to the new issue view and add any other participant, it will erase everyone in the field.